Nip roll assembly for stuffer box crimping device

ABSTRACT

A nip roll assembly in the yarn feed means for a stuffer box crimper which includes a pair of nip rolls rotatably mounted on parallel axes or shafts, a peripheral collar on each shaft, a nip ring fastened to each collar by a transition fit and a pair of removably secured clamping means pressing axially on outwardly facing surface portions of each collar and its nip ring so as to couple the shaft for torque transmission to the nip ring. This assembly makes it practical to repair or replace worn or damaged nip rollers while ensuring proper transmission of torque to the yarn contacting surfaces of the rollers.

United States Patent [191 Fuchs et al.

[451 Nov. 19, 1974 NIP ROLL ASSEMBLY FOR STUFFER BOX CRIMPING DEVICE Inventors: Rudolf Fuchs, Kassel; Kurt Glieschke, Bonaforth, both of Germany Akzona Incorporated, Asheville, NC.

Filed: Jan. 15, 1973 Appl. No.: 323,945

Assignee:

Foreign Application Priority Data Feb. 11, 1972 Germany 7205130 US. Cl. 28/145, 29/125 Int. Cl D02g 1/12 Field of Search 28/l.6, 72.14; 29/123,

References Cited UNITED STATES PATENTS 12/1936 Rose 29/125 2,324,050 7/1943 Shelley 29/125 3,432,902 3/1969 Rackoff et al.. 29/125 3,581,659 6/1971 Bryer 29/123 X 3,680,181 8/1972 Heijnis 28/l.6

Primary Examiner-Louis K. Rimrodt Attorney, Agent, or Firml0hnston, Keil, Thompson & Shurtleff ABSTRACT A nip roll assembly in the yarn feed means fora stuffer box crimper which includes a pair of nip rolls rotatably mounted on parallel axes or shafts, a peripheral collar on each shaft, a nip ring fastened to each collar by a transition fit and a pair of removably secured clamping means pressing axially on outwardly facing surface portions of each collar and its nip ring so as to couple the shaft for torque transmission to the nip ring. This assembly makes it practical to repair or replace worn or damaged nip rollers while ensuring proper transmission of torque to the yarn contacting surfaces of the rollers.

6 Claims, 3 Drawing Figures This invention generally relates to devices for use in textile machines and more particularly to the stuffer box crimping of synthetic filaments, especially yarns, tows or the like. Such devices typically comprise a stuffer box and, disposed near one end of it, a pair of cooperating, oppositely driven nip rolls or nip roll assemblies which are. urged against each other and by means of which the filaments are supplied to the stuffer box. These nip roll assemblies include a pair of parallel shafts which are rotatably mounted in the housing of the textile machine, and a pair of rings mounted on these two shafts, respectively, and referred to hereinafter as nip rings, which provide the actual circumferentia'l operating or nipping surfaces between which the filaments or the like are fed to the stuffer box. The invention is specifically concerned with improvements in the'design of each nip roll assembly.

l-leretofore, each shaft of such a nip roll assembly has been provided with a collar of a width substantially corresponding to the effective roller gap width. The nip ring at the circumference. Additional reasons for the failure of the materials involved are sudden larger and mostly intermittent overstresses which may occur, for

. example, when knots or bulges in the yarn enter into provide, in stuffer box crimping devices, a connection rings have been made of a hardened steel, eachbeing secured to its corresponding shaft collar by heat shrinking. This construction has been an almost universally accepted practice. Underlying the use of this prior art technique was the general assumption that, becasue of the magnitude of the torque to be transmitted and because of the shock loads involved, the connection between a nip ring and its shaft had to be established by a transverse force fit, producing a uniform surface pressure along the inner circumference of the nip ring in short by heat shrinking. The conventional hub-to-shaft connection by means of splines, keys or the like and grooves cannot be used because this type of coupling is liable to give rise to the danger of the so-called notch effect, particularly due to the alternating stresses involved. 1

The operating surfaces of the nip rings must be machined with great precision, from the standpoint both of dimensional accuracy and smoothness of finish, so that the circumferential speeds of these surfaces are as nearly equal as possible and so that the length of the nip gap between the two rings can be adjusted precisely and without variation of this length over the width of the gap. This is necessary to ensure that the operative forces in the nip gap act uniformly on the filaments or yarn being crimped.

In the operation of the known device the surface of the nip ring is subjected to abrasion and to normal wear and tear. The wear of the heat shrunk nip rings of the prior art could be compensated for, to a limited extent, by regrinding and in some cases by microfinishing. However, after a lower limit in diameter has been reached or in case of severe deterioration of the operating surface, the nip rings must be changed. Severe deterioration of the nip surface may occur, for example, if, due to friction on the side wall of the stuffer box or because of abrasion by theyam 0r scoring of the operating surface by the entering filaments, the edges of the nip rings become roundedoff. Frequently, too, the nip rings rupture during operation, thus requiring replacement. The cause of such rupture of the ringis believed to be the high static prestressing of the rings incident to'the practically uncontrollable heat shrinking operation, in conjunction with the alternating stresses occurbetween the shaft and the nip ring of a nip roll assembly which avoids the'above disadvantages of the prior art technique. It is a more specific object of the invention to provide a connection between these parts which, on the one hand, ensures slipless torque transmission, even in the event of momentary load peaks and which, on the other hand, can readily be undone and again reestablished upon replacement of worn parts. Thus, it must be possible to easily remove and replace the nip ring on the shaft while still permitting a satisfactory yarn feed and avoiding damage due to alternating stresses.

According to the invention these objects are met by fitting each nip ring to a collar of the corresponding shaft with a transition fit and by providing as a part of each nip roll assembly, two clamping rings which are placed over the two ends of the corresponding shaft for lodgment on the two sides, respectively, of the collar. The assembly further includes means, such as a plurality of circumferentially spaced bolts, for removably securing the two clamping rings to each other so that the opposing faces of the clamping rings are pressed against axially outwardly facing surface portions of the collar and of the corresponding nip ring. The resulting axially oriented clamping forces thus couple the shaft to the nip ring for smooth and slipless torque transmis- 81011.

The clamping connection of the invention is easy to manufacture and, as evidenced by the successful operation of a stuffer box crimping device using this connection, is fully satisfactory in performance. Moreover, if, because of wear phenomena, the nip ring must be replaced or removed for reconditioning, the formerly time-consuming and costly repairs can be carried out in a local repair shop or, if necessary, at the textile machine itself and in mush less time and at greatly reduced cost. The device according to the invention has the advantage, furthermore, that in the proposed connection between the shaft and the replaceable nip ring the high static pressures that existed in the case of the heat shrinking technique of the prior art, are no longer present. A frequent cause of material or structural failure is thus eliminated. The connection used in the assembly according to the invention, therefore, yields advantages far beyond those of the heat shrinking type of coupling while avoiding the disadvantages of this prior art technique.

An illustrative embodiment of the invention will now be described with reference to the accompanying drawing in which:

FIG. 1 is a diagrammatic side view, partly in section taken along line [-1 of FIG. 2, of a stuffer box crimping device with nip roll assemblies constructed according to the invention,

FIG. 2 is atop view, partly in section taken along line IIII of FIG. I, of the device shown in FIG. 1; and

FIG. 3 is a detail, illustrated in enlarged scale, of the nip roll assembly shown in the right-hand portion of FIGS. 1 and 2.

In FIGS. 1 and 2 the reference numerals l and 2 designate the two cooperating nip roll assemblies of the stuffer box crimping device of the illustrated embodiment. These two nip roll assemblies are laterally urged against each other, and are rotated by driving means in opposite directions as indicated by thearrows 3'and 4, using will known drive means which are not illustratedin the drawing. Thenip roll assemblies act to force the filaments or yarn therebetween in the direction of arrow 5 and to feed them into the adjacent upper end of the stuffer box 6 for temporary retention and crimping therein. It may be mentioned at this point that the term filaments is used herein in a generic sense to denote various kinds of filamentary structures, such as fibers, filaments, yarns, tows or the like. The filaments may also be those which have been subjected to other processing prior to being fed to the stuffer box crimping device shown in the drawing; for example, the yarn may have been first spread into a ribbon or tow by conventional means. The individual yarn or filament treating devices or their combinations are ordinarily grouped in banks or rows and/or tiers to provide a multi-unit textile machine.

The side walls of stuffer box 6 are formed by plates 7 and 8, the former of which is shown partlyin section 1 in FIG. 1. The other two sides of stuffer box 6 are closed by walls 9 (FIG. 2) and 10'(FIGS. l and 2). Wall 9 can be opened, in a manner well known in this art, by means of an hinge 11,11, to provide access to the filaments. The outlet end of the stuffer box has a hinged flap 12 which is loaded by a weight 13 (FIG. 1 only) so that a desired, adjustable counterpressure is exerted on the mass of yarn stored or retained in stuffer box 6.

Nip roll assemblies 1 and 2 comprise shafts l4 and 15, respectively, which are rotatably supported in-mutually parallel relationship in the housing of the textile machine (not shown). These nip roll assemblies further comprise nip rings 16,17 which are coupled to their respective shaftsaccording to the requirements of the present invention, the two nip rings providing the operating or yarn contacting surfaces of the nip roll assemblies. Whereas the two shafts are made of a round steel of commercial grade, the nip rings are made from highgrade hardened steel with a microfinished yarn contacting surface. In the peripheral region where nip ring 16 is fitted to shaft 14 the latter has an integral collar 18. Similarly shaft 15 .has an integral collar 19 around the peripheral region where nip ring 17 is fitted to shaft 15.

The fit between nip ring 16 and collar 18 of shaft 14, as well as the fit between nip ring 17 and collar 19 of the shaft 15, is a transition fit. Preferably, as one example, if the basicbore or inner diameter of the nip ring has the tolerance designation H5, the corresponding collar or shaft diameter at the collar can have the tolerance designation j6. In this connection it will be recalled that in the ISO system of tolerances to which this example applies, the capital letter H in the designation H5 denotes a basic hole and the numeral 5 denotes the a tolerance grade of the hole; and in the designation j6 1 the lower case letter j denotes a shaft providing, when assembled with a hole of the basic size, the allowance j and the numeral 6 denotes the tolerance grade of the shaft. The result of this exemplary combination is a transition fit. The term transition fit" thus has a restricted and well known meaning in the mechanical arts and is used throughout this specification-and in the accompanying claims in this restricted sense.

In the prior art connections, the shaft collars to which the nip rings were fastened by heat shrinking had a width substantially the same as that'of the nip rings. In' the present case in accordance with the embodiment of the invention shown in the drawing, the collars l8, l9

on the two shafts have a width which is less than that of the operating surface of. the corresponding nip rings 16, 17. Referring particularly to the nip roll assembly shown in the right-hand portion of FIGS. 1 and 2, and to the detail thereof illustrated in larger scale in FIG. 3, it will be noted that the shoulders on the sides of collar 19 provide two annular recesses designated 22 and 23, respectively, and generally complementary annular recesses are formed in the two sides, respectively, of nip ring 17. As will be seen fromthe drawing, clamping rings 27 and 28, respectively, are received by the composite annular recesses thus created. Preferably, and as illustrated in the drawing, the depth of these recesses is of a sufficient magnitude to prevent the clamping rings from protruding beyond the planes defined by the end faces of the nip ring. The construction of the other nip roll assembly 1 is the same as just described for assembly 2; the two clamping rings of assembly 1 are designated as 20 and 21 in the drawing.

Both nip rings have a number of axially oriented bores, designated by the numeral 25 in FIG. 3, which are uniformly distributed circumferentially of the nip ring, and the shafts of bolts 24 are passed through these bores to provide a means by which the two cooperating clamping rings, e.g., 27 and 28, may be removably secured together. At least one of these two clamping rings also has a corresponding number of bores 31 (see FIG. 3) in alignment with the core 25 in the corresponding nip ring, and it has a corresponding number of recesses 32, each for receiving the head of the respective bolt, this head being specifically designated as 33 in FIG. 3. The other end of each bolt is screwed into threads tapped at corresponding locations into the cooperating clamping ring. Actually, the preferred arrangement, indicated in FIG. 1, is to insert the bolts of the circumferential series-alternately from one side and the other of each assembly with the clampingrings being drilled or tapped accordingly.

It will be appreciated from the foregoing description thatby tightly clamping the collar of each shaft, to-

gether with the body portion of the corresponding nip ring, between the two associated clamping rings by means of the bolts, the axial forces exerted by the clamping rings ensure the smooth transmission of the required torque between the shaft and the nip. ring without slippage and in a manner which also facilitates ready replacement of the nip ring. Yet, interference I with the operating surface of the nip ring is avoided, and the shortcomings of the heat shrinking technique of the prior art are eliminated without compromising the compactness and accurate dimensions of the assembly.

According to an especially preferred implementation of the invention as shown in greatest detail in FIG. 3, correspondingly drilled, washer-shaped, thin sheet metal members 26 made of a deformable material such as aluminum, copper, rolled lead, high-grade steelor the like, are interposed in the clamping connection.

These annular members may have a thickness of up to 3 mm, preferably between 0.5 and 1.5 mm, and they may also be profiled in a radial direction if desired. These members 26 serve to render the transmission of the surface pressure from-the clamping rings to the clamped annular surfaces and, more particularly, they serve to compensate for slight differences in manufacturing tolerances. Upon tightening of the bolts the sheet metal members 26 deform in such a way to compensate for any minor dimensional differences in the width of the shaft collar and the width of the corresponding body portion of the nip ring, and they further help to ensure that, by means of the large forces axially exerted by the bolts, the nip rings l6, 17 are properly and securely fastened to the shafts 14, without slippage. In this respect, these inserts act in the nature of locking washers. It will also be clear that when installing new nip rings, only the annular members 26 need to be replaced while the clamping rings 20, 21 or 27, 28 may continue to be used. Thus, replacement of the nip rings for the purpose of reconditioning, repair or the like may be readily accomplished and with very little cost directly at the machine itself and/or in any local repair shop.

The stuffing box crimper is operated in the conventional manner with the yarn or filaments being drawn in the direction of the arrow 5 and stuffed into the stuffer box 6. However, even when knots or similar variations in the yarn thickness place temporary high loads perpendicularly to the axis of rotation of the nip rolls, the combination of a transition fit and cooperating clamping rings prevents the nip rolls from becoming damaged while still providing a positive torque during the entire crimping operation. At the same time, the nip rings can be replaced without difficultly as required by normal wear over a period of time.

The invention is hereby claimed as follows:

1. In a stuffer box device for crimping synthetic filaments including a stuffer box and a pair of cooperating nip roll assemblies which are disposed adjacent one end of said stuffer box and are driven in opposite directions to feed said filaments into said box, each said assembly including a shaft and a nip ring joined to said shaft, the improvement which comprises an assembly in which each nip ring is fitted to a collar of its corresponding shaft with a transition fit, two clamping rings being disposed about the corresponding shaft of each nip ring on the two sides, respectively, of said collar, and means for removably securing said clamping rings to each other so as to press the opposing faces of said clamping rings against axially outwardly facing surface portions of said collar and of the corresponding nip ring, thereby coupling said shaft for torque transmission to said nip ring.

2. A device as claimed in claim 1 wherein each nip ring has a plurality of circumferentially spaced apertures extending therethrough in a direction parallel to its axis and said securing means comprises a plurality of bolts extending between said clamping rings through said apertures.

3. A device as claimed in claim 1 wherein said assembly further includes deformable means interposed between said opposing faces of said clamping rings and said surface portions'of said nip ring.

4. A device as claimed in claim 3 wherein said deformable means comprises thin annular members of sheet metal clamped between said opposing faces of said clamping rings and said surface portions of said nip ring and said collar.

5. A device as claimed in claim 1 wherein said two clamping rings are received by two annular recesses in said shaft as provided by two shoulders, respectively, of said collar and by two generally complementary annular recesses formed in said nip ring on both sides, re-

' 'spectively, thereof.

6. A device as claimed in claim 5 wherein said recesses are of a depth such that said clamping rings do not 

1. In a stuffer box device for crimping synthetic filaments including a stuffer box and a pair of cooperating nip roll assemblies which are disposed adjacent one end of said stuffer box and are driven in opposite directions to feed said filaments into said box, each said assembly including a shaft and a nip ring joined to said shaft, the improvement which comprises an assembly in which each nip ring is fitted to a collar of its corresponding shaft with a transition fit, two clamping rings being disposed about the corresponding shaft of each nip ring on the two sides, respectively, of said collar, and means for removably securing said clamping rings to each other so as to press the opposing faces of said clamping rings against axially outwardly facing surface portions of said collar and of the corresponding nip ring, thereby coupling said shaft for torque transmission to said nip ring.
 2. A device as claimed in claim 1 wherein each nip ring has a plurality of circumferentially spaced apertures extending therethrough in a direction parallel to its axis and said securing means comprises a plurality of bolts extending between said clamping rings through said apertures.
 3. A device as claimed in claim 1 wherein said assembly further includes deformable means interposed between said opposing faces of said clamping rings and said surface portions of said nip ring.
 4. A device as claimed in claim 3 wherein said deformable means comprises thin annular members of sheet metal clamped between said opposing faces of said clamping rings and said surface portions of said nip ring and said collar.
 5. A device as claimed in claim 1 wherein said two clamping rings are received by two annular recesses in said shaft as provided by two shoulders, respectively, of said collar and by two generally complementary annular recesses formed in said nip ring on both sides, respectively, thereof.
 6. A device as claimed in claim 5 wherein said recesses are of a depth such that said clamping rings do not protrude beyond the planes defined by the end faces of said nip ring. 